18. Match List I with List II and select the correct answer:
List I List II
A. Ultimate strength 1. Internal structure
B. Natural strain 2. Change of length per unit instantaneous length
C. Conventional strain 3. Change of length per unit gauge length
D. Stress 4. Load per unit area
A B C D
(a) 1 2 3 4
(b) 4 3 2 1
(c) 1 3 2 4
(d) 4 2 3 1